Components malfunction in internal combustion engines give rise to numerous problems and it is desirable to have a reliable method for detecting them. For example, an incorrect combustion within one or more cylinders in an internal combustion engine with controlled ignition is generally indicated as misfire. Misfire events have very negative effects on engine performance, on emissions values and could also cause damages on the catalyst. European and OBDII legislation require detecting misfire events causing excess emissions.
Most current cylinder misfire detection methods use the angular acceleration of the drive shaft in order to find a misfiring cylinder. As already well known these methods are not perfectly suitable since the angular acceleration of the drive shaft is influenced not only by misfire but also, for example, by the roughness of the road and by very sudden decelerations. Other detection methods use other signals or detailed mathematical models in order to estimate the misfire condition.
The most widespread method for detecting misfire treat this argument as a component monitoring, comparing the value of a signal built from directly measured signals (for example the phonic wheel angular position) with some thresholds: if these thresholds are exceeded then a misfire is detected. This approach may lead to false detections and, in general, to an unsuitable way to monitor the combustion since an issue on the combustion could be the effect of different phenomena. So a more suitable logic is needed in order to identify, during the engine life, the misfire events avoiding false detections. Moreover, known pattern recognition models are only static models that do not take into account, during the engine life, the variations of the engine system having effect on the misfire detection.
At least a first object is to provide a method of detecting components malfunction or other undesirable events that takes into account possible variations of the components behavior during engine life and the associate components drift. At least a further object is to provide a malfunctioning detection method suitable for detecting misfire events and that takes into account possible variations during engine life of the phenomena associated and of the possible components drift. At least another object is to provide a malfunction detection method for components of an internal combustion engine that does not use complex devices and that takes advantage from the computational capabilities of the Electronic Control Unit (ECU) of the vehicle. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.